/*
 * Copyright (c) 2006 Mark Woodman
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */
package com.xml.feed;

import com.sun.syndication.feed.synd.*;
import com.sun.syndication.io.*;
import com.totsp.xml.syndication.content.ContentModule;
import java.io.*;
import java.net.URL;
import java.util.*;

/**
 * FeedWarmer demonstrates how to use ROME to read, manipulate
 * and publish an RSS or Atom feed.   This example adds a footer
 * of "immediate action" links to each feed item.
 *
 * @author Mark Woodman
 *
 */
public class FeedWarmer
{
    /** Namespace URI for content:encoded elements */
    private static String CONTENT_NS =
            "http://purl.org/rss/1.0/modules/content/";

    /** Parses RSS or Atom to instantiate a SyndFeed. */
    private SyndFeedInput input;

    /** Transforms SyndFeed to RSS or Atom XML. */
    private SyndFeedOutput output;

    /**
     * Default constructor.
     */
    public FeedWarmer()
    {
        input = new SyndFeedInput();
        output = new SyndFeedOutput();
    }

    /**
     * Add FeedWarmer footer to all items of any feed,
     * then republish as format specified in OUTPUT.
     * @param url           The feed URL to input
     * @param outFormat     The feed type to output.  Can be:
     *                      rss_0.9, rss_0.91, rss_0.92, rss_0.93,
     *                      rss_0.94, rss_1.0, rss_2.0, atom_0.3,
     *                      or atom_1.0
     * @throws IOException
     * @throws FeedException
     */
    public String warmFeed(URL url, String outFormat)
            throws IOException, FeedException
    {
        // Load the feed, regardless of RSS or Atom type
        SyndFeed feed = input.build(new XmlReader(url));

        // Set the output format of the feed
        feed.setFeedType(outFormat);

        // Modify the feed title
        String newTitle = feed.getTitle() + " (Warmed)";
        feed.setTitle(newTitle);

        // Iterate through feed items, adding a footer each item
        Iterator entryIter = feed.getEntries().iterator();
        while (entryIter.hasNext())
        {
            SyndEntry entry = (SyndEntry) entryIter.next();
            addFooter(entry);
        }

        // Generate XML in output format, regardless of original
        StringWriter writer = new StringWriter();
        output.output(feed, writer);
        return writer.toString();
    }

    /**
     * Add FeedWarmer footer to an entry.
     * @param entry
     */
    private void addFooter(SyndEntry entry)
    {
        // Prep variables used in loops
        String title = entry.getTitle();
        String link = entry.getLink();

        // Use the add-on ContentModule to handle
        // <content:encoded/> elments within the feed
        ContentModule module =
                ((ContentModule) entry.getModule(CONTENT_NS));

        // If content:encoded is found, use that.
        if(module!=null)
        {
            // Container for footer-appended HTML strings
            List newStringList = new ArrayList();

            // Iterate through encoded HTML, creating footers
            Iterator oldStringIter =
                    module.getEncodeds().iterator();
            while (oldStringIter.hasNext())
            {
                String original = (String) oldStringIter.next();
                newStringList.add(createFooter(original,
                                  link, title));
            }

            // Set new encoded HTML strings on entry
            module.setEncodeds(newStringList);
        }
        else
        {
            // Fall back to adding footer in <description/>
            // This results in escaped HTML.  Ugly, but common.
            Iterator contentIter = entry.getContents().iterator();
            while (contentIter.hasNext())
            {
                // Target the description node
                SyndContent content =
                        (SyndContent) contentIter.next();

                // Create and set a footer-appended description
                String original = content.getValue();
                content.setValue(createFooter(original,
                                 link, title));
            }
        }
    }

    /**
     * Create a feed item footer of immediate actions
     * by using information from the feed item itself
     * @param original  The original text of the feed item
     * @param link      The link for the feed item
     * @param title     The title of the feed item
     * @return
     */
    private String createFooter(String original, String link,
                                String title)
    {
        // Use StringBuffer to create a sb
        StringBuffer sb = new StringBuffer(original);
        sb.append("\n\n<div class='feedwarmer'><hr/>");
        sb.append("<i>Getting Warmer:</i> ");

        // Add email link using title and item link
        sb.append("<a href='mailto:?body=Check this out: ");
        sb.append(link).append("'>Email this</a> | ");

        // Add delicious link using item title link
        sb.append("<a href='http://del.icio.us/post/?url=");
        sb.append(link).append("&title=").append(title);
        sb.append("'>Add to delicious</a> | ");

        // Add Google Blogs Search link using item title
        sb.append("<a href='http://blogsearch.google.com/");
        sb.append("blogsearch?hl=en&q=").append(title);
        sb.append("'>Blog Search this</a>");

        // Finish and return the sb
        sb.append("</div>\n");
        return sb.toString();
    }

    /**
     * Main method to demo from command line.
     * @param args        args[0] must be the URL of a feed
     * @throws Exception
     */
    public static void main(String[] args) throws Exception
    {
        // Create instance
        FeedWarmer warmer = new FeedWarmer();

        // "Warm" a feed using URL passed in,
        // designating the feed output desired
        String warmedFeed = warmer.warmFeed(new URL(args[0]),
                                            "rss_2.0");
        // Print to console to demo results
        System.out.println(warmedFeed);
    }

}